Surface characteristics observed over the central tropical Indian Ocean during INDOEX IFP99

The present study is based on the observations carried out over the Indian Ocean from the Indian research vessel ORV Sagar Kanya during the intensive field phase of the Indian Ocean Experiment in January-March 1999. The study area spanned from 15°N to 20°S in the central Indian Ocean. Near surface variations and surface fluxes along the cruise track are presented. A comparison of near surface characteristics over the Indian Ocean and tropical west Pacific has been made. It is observed that the average difference between the sea surface temperature and air temperature at 10 m height was 0.7 °C over the study area, nearly half of that observed over the tropical west Pacific. A comparison between observed and NCEP reanalysis surface data has been made. We find good agreement between ship measured and NCEP reanalysis surface pressure, specific humidity and wind fields. On the other hand, surface air temperature in the reanalysis tends to be low compared to observations. The components of the net surface heat flux compare better in the north Indian Ocean than in the southern Indian Ocean.